The present disclosure generally relates to depth sensing, and specifically relates to a non-mechanical beam steering for depth sensing in virtual reality (VR) and augmented reality (AR) systems.
A fully addressable one-dimensional scanning or two-dimensional scanning process that runs at fast rates is desired for depth sensing in VR or AR systems. Much like human perception, the scanning system needs to operate in two modes: a large-scale mode for scanning of, e.g., walls, tables, chairs, and the like, and a small-scale mode for scanning of e.g., hands, surface reliefs, textures, and the like. A preferred scanning system would have the ability to quickly pull in large scale objects and then to dwell on fine details. A static depth sensing system that operates at a large and small scale typically puts the system design in conflict. On a transmitter side, a large number of individual beams required for accurate sampling reduces a power in each beam and a signal-to-noise ratio (SNR). To provide accurate sampling, a large amount of input power for generating scanning beams is required. A static depth sensing system with a wide field-of-view would lack resolution on a receiver side. Depth sensing systems that can both scan and dwell are typically mechanically based systems. However, a scanning pattern generated by a mechanical depth sensing system is static and cannot dwell on a particular location in a surrounding area.
The conventional approaches for solving the large scale-small scale conflict generally fall into three categories: large/full scale static room illumination, a fixed illumination obtained by a mechanically driven dynamic system, and a variable illumination obtained by a mechanically driven dynamic system. The conventional mechanically driven dynamic sensing system generates a fixed scanning pattern that can sweep a room volume. This approach reduces a required laser power and can provide enough detail to accurately reconstruct the volume. However, the mechanically driven dynamic sensing system generates a fixed scanning pattern and is not addressable. The system resolution is fixed by a number of spots in the fixed scanning pattern. The mechanically driven dynamic sensing system that generates a fixed scanning pattern is typically implemented with scanning mirrors. The conventional mechanically driven dynamic sensing system may also generate a variable scanning pattern that can sweep a room volume. This approach reduces a required laser power and can provide enough detail to accurately reconstruct the volume. However, the mechanically driven dynamic sensing system with the variable scanning pattern is slow and mechanically complex.